Water Journal : Water Journal April 2012
automation and telemetry 122 APRIL 2012 water technical features Abstract A medium-sized water utility in south- west Germany has installed innovative technology that permanently monitors the network and alerts the central office as soon as a leak appears. The average run-time of a leak event has been reduced to one-and-a-half days, thus enabling reduction of water losses to lower levels than ever before. In addition to this, the effort and cost of localisation has been reduced by 98%, with all analysis being performed in the office. Introduction Albstadt is a town located in south- west Germany, about 80km south of Stuttgart. Albstadtwerke is the utility network distribution provider in this region, supplying potable water, natural gas and electricity. In addition to managing and maintaining the local distribution assets in Albstadt, Albstadtwerke operates and maintains two more potable water distribution networks, seven natural gas distribution networks and an electricity supply. Albstadtwerke is efficiently run with 80 employees for the entire operation and construction of its networks and facilities. It has been a corporate policy for many years to continuously evaluate current methodologies and introduce new innovative methods in leak detection and trenchless pipe installation. The Challenge Figure 1 shows a picture of the Albstadt region, which is spread across three valleys and has a height variation of 400m. This geographical landscape creates a number of operational challenges, including: • A large number of different pressure zones; • Long sections of trunk main; and • Long distances for maintenance staff to drive to reach the extremities of the network. Approximately 50% of the water supply comes from our raw water catchment and is processed in several stages at our water plant to produce high-quality drinking water. The other 50% is purchased from a total of three suppliers. We are about 80km away from the Lake of Constance, which is one of the biggest lakes in Europe. Our current Non-Revenue Water is 20% (500,000 cubic metres), which has increased from 10% five years ago. The increase in the NRW percentage is due to a 50% reduction in total consumption; our water loss has remained constant. The ground is limestone, which means that almost no leak is visible on the surface as there is always good drainage. We have had massive leaks of 25L/S disappear underground (Figure 2). Our first investigation was in the Braunhartsberg reservoir zone. This zone consists of 52km of pipework with a mixture of cast iron, UPVC and ductile iron, and it contains most of the factors that make leak detection difficult. Water Loss Innovations Our first strategy to improve network efficiency was to install a flow meter on the reservoir outflow and have the data sent to our office on a daily basis with alarms to advise us if there was an increase in minimum night flow (MNF). This is shown in Figure 3. F Tantzky TELEMETRY CUTS THE COST OF LEAK DETECTION Figure 1. The Albstadt region in Germany. Figure 2. Typical limestone ground. Figure 3. Flow meter installation.
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